A protester carrying a sign during the People’s Climate March in the Manhattan borough of New York, on Sunday. Photo: Carlo Allegri/Reuters

An international day of action on climate change brought thousands of people on to the streets of New York City and London on Sunday.

Organisers estimated that some 310,000 people, including UN Secretary-General Ban Ki-moon, former US Vice President Al Gore, actor Leonardo DiCaprio and elected officials from the US and abroad joined the People’s Climate March in New York, ahead of today’s UN hosted summit in the city to discuss reducing carbon emissions that threaten the environment.

In London, celebrities including actress Emma Thompson, musician Peter Gabriel and designer and activist Vivienne Westwood, joined an estimated 40,000 people to march through Westminster calling on politicians to tackle the issue.

Other such events were held in France, Afghanistan and Bulgaria. But the New York rally was the largest single protest ever held on the topic of climate change.

“The march numbers beat our wildest expectations,” said Ricken Patel, executive director of activist group Avaaz, which organised the march. “Climate change is not a green issue anymore, it’s an everybody issue.”

Ban, wearing a T-shirt that read “I’m for climate action” marched arm-in-arm with British primatologist Jane Goodall and French Ecology Minister Segolene Royal.

“This is the planet where our subsequent generations will live,” Ban told reporters. “There is no Plan B, because we do not have Planet B.”

DiCaprio marched towards the front of the group, with members of an Ecuadorean tribe who have fought a years-long legal battle with Chevron Corp. over Amazon pollution.

“This is the most important issue of our time,” he said. “I’m incredibly proud to be here.”